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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

36209 results found.

  1. GRB 250706B: iTelescope optical observations
  2. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  3. GRB 250706B: SVOM/VT optical observation
  4. GRB 250706B: TRT bright optical counterpart detection
  5. GRB 250706A: GROWTH-India Telescope optical upper limit
  6. GRB 250706B: SVOM detection of a long burst
  7. GRB 250706A: Swift detection of a burst
  8. GRB 250704B: Swift-XRT refined Analysis
  9. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  10. GRB 250703A: EIRSAT-1 GMOD Detection
  11. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  12. GRB 250704B: Swift/UVOT Upper Limits
  13. GRB 250704A: Swift/UVOT Detection
  14. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  15. GRB 250704B: Insight-HXMT detection
  16. Konus-Wind detection of GRB 250703A
  17. IPN triangulation of GRB 250703A
  18. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  19. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  20. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  21. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  22. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  23. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  24. GRB 250702F: Kilonova-Catcher optical afterglow detection
  25. GRB 250702F: Monte Agliale Observatory optical observations
  26. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  27. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  28. EP250704a / GRB 250704B: JinShan optical observations
  29. GRB 250704A: SVOM/VT optical observation
  30. EP250704a / GRB 250704B: SAO RAS optical observations
  31. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  32. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  33. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  34. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  35. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  36. GRB 250702A: Insight-HXMT detection
  37. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  38. EP250704a / GRB250704B: Swift-XRT counterpart detection
  39. GRB 250704A: Swift-XRT afterglow detection
  40. GRB 250702B / EP2050702a: FTW optical and NIR observations
  41. Konus-Wind detection of GRB 250702F
  42. EP250704a / GRB 250704B - REM observations
  43. GRB 250702F: GROWTH-India Telescope optical observations
  44. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  45. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  46. EP250704a: Einstein Probe detection of an X-ray transient
  47. GRB 250704B: SVOM/GRM observation of a short burst
  48. GRB 250702F: optical photometry from Konkoly
  49. GRB 250704A: REM detection of the optical afterglow
  50. GRB 250702F: SVOM/VT optical observation
  51. GRB 250704A: SVOM detection of a burst
  52. GRB 250702F: Swift/UVOT Detection
  53. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  54. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  55. Fermi GRB 250703A: Global MASTER-Net observations report
  56. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  57. GRB 250702F: Swift-XRT refined Analysis
  58. GRB 250702F: Fermi GBM Observation
  59. GRB 250702F: Leavitt Observatory optical observations
  60. GRB 250702F: AKO Optical Afterglow Detection
  61. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  62. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  63. GRB 250702A: GECAM-B detection
  64. GRB 250702F: Skynet Optical Observations
  65. GRB 250424A: VIRT Optical Upper Limit
  66. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  67. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  68. GRB 250702F: TRT Optical Observation
  69. GRB 250703A: DDOTI Optical Upper Limit
  70. GRB 250702F: REM optical afterglow detection
  71. GRB 250702F: DDOTI Optical Observation
  72. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  73. GRB 250703A: Fermi GBM Final Real-time Localization
  74. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  75. GRB 250702F: COLIBRÍ Observations of the Afterglow
  76. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  77. Fermi GRB 250702E: Global MASTER-Net observations report
  78. Fermi GRB 250702B: Global MASTER-Net observations report
  79. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  80. GRB 250702F: Enhanced Swift-XRT position
  81. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  82. GRB 250702F: NOT observations of the optical afterglow
  83. GRB 250702F: MASTER optical afterglow observation
  84. Fermi GRB 250702F: Global MASTER-Net observations report
  85. Fermi GRB 250702C: Global MASTER-Net observations report
  86. GRB 250702F: GOTO optical counterpart detection
  87. GRB 250702F: Ondrejov D50 optical afterglow detection
  88. GRB 250702F: Swift detection of a burst with an optical counterpart
  89. Swift GRB 250702F: Global MASTER-Net observations report
  90. GRB 250702F: Fermi GBM Final Real-time Localization
  91. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  92. GRB 250702E: Fermi GBM Final Real-time Localization
  93. Konus-Wind detection of GRB 250627A
  94. IPN triangulation of GRB 250627A (short)
  95. GRB 250702A: Fermi GBM Detection
  96. GRB 250702D: Fermi GBM Final Localization Correction
  97. GRB 250702C: Fermi GBM Final Real-time Localization
  98. GRB 250702B: Fermi GBM Final Real-time Localization
  99. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  100. GRB 250702A: Fermi GBM Final Real-time Localization

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